A new class of thermoplastic polymers, known as thermotropic liquid crystal polymers ("LCP"), has recently been introduced to the marketplace. These polymers combine the advantageous feature of moldability with multidirectional mechanical strength superior to other thermoplastics formerly available. Generally, these new LCP materials are polyesters made up of planar, linear disubstituted aromatics. Examples of some LCPs currently in use are p-hydroxybenzoic acid, 5 p-hydroquinone, 4,4'-dihydroxybiphenyl and 2-hydroxy, 6-napthenoic acid.
Other LCPs would appear commercially attractive if either 2,6-dihydroxynaphthalene or 2,6-dicarboxynaphthalene were readily available. Unfortunately, these materials are not commercially produced because cheap, readily available feed stocks do not exist. A viable feed stock, which is convertible into either the dihydroxy or dicarboxy monomers, based upon known technology, is 2,6-diisopropylnaphthalene.
Before proceeding with any description of the isopropylation reaction system, it is important to first review the nomenclature and numbering scheme for the various substituted naphthalene isomers. Equation 1 shows the positional reference numbers. Non-hydrogen bearing carbons are unnumbered because no substitution takes place in these positions.